1. Technical Field
The invention relates generally to cold cathode luminescent field emission devices and, particularly, to a field emission plane light source employing a getter to exhaust unwanted gas from therein, thereby ensuring a high degree of vacuum. The invention also relates to a method for making a field emission plane light source.
2. Discussion of Related Art
Recently, with the development of the plane display technology, field emission display (FED) technology has been paid more attention. FED technology potentially offers, e.g., higher brightness, lower energy consumption, broader visual angle, higher contrast than possible with liquid crystal or plasma displays. FED technology could be utilized in many fields including, e.g., personal computers, mobile communications, flat screen displays/televisions, etc.
Generally, a field emission plane light source is employed in a field emission display as a light source. A nanotube-based field emission plane light source usually includes a cathode having carbon nanotubes and an anode having a fluorescent layer. In use, a strong electrical field is provided for between the cathode and anode, the strong electrical field excites the carbon nanotubes of the cathode to emit electrons, and the electrons bombard the fluorescent layer of the anode to thereby produce visible light. For a field emission plane light source, a high degree of vacuum within an interior portion thereof is a virtual necessity. In general, the better of the degree of vacuum that is able to be generated and maintained within the field emission plane light source during the sealing process, the better of the field emission performance thereof is. To maintain the degree of vacuum within a desired range, a conventional way is to provide a getter in the inner portion thereof. Such a getter is able to exhaust a gas produced by the fluorescent layer and/or any other residual gas remaining within the field emission plane light source upon sealing and evacuation thereof. The getter is suitably selected from a group consisting of non-evaporable getters and evaporable getters.
For the evaporable getter, a high-temperature evaporating process has to be provided during the fabrication of the field emission plane light source, and a plane/surface arranged in the inner portion of the field emission plane source has to be provided to receive the evaporated getter. Thus, the cost of the fabrication of the field emission plane light source can be expected to increase, and the cathode and anode electrodes are prone to shorting during the high temperature evaporating process, thereby increasing the chance of the failure of the field emission plane light source. For the non-evaporable getter, it is typically located at a position away from the cathode, and, thus, the degree of vacuum of portions near to the cathode tends to be poorer, in the short-term, than that of portions near to the getter, at least until internal equilibrium can be reached, thereby decreasing the field emission performance of the cathode or at least potentially resulting in a fluctuating performance thereof.
What is needed, therefore, is a field emission plane light source that overcomes the above-mentioned shortcomings to ensure a high degree of vacuum thereof, thus providing a better and more steady field emission performance during the use thereof.
What is also needed is a method for making such a field emission plane light source.